Observations on Breeding Biologyof some New Guinea Murid Rodents

Breeding records are given for 10 murine rodents from the Eastern Highlands District of Papua New Guinea. Reduced breeding activity through the dry season is apparent for Rattus exulans, R. ruber and Melomys rufescens, with a cessation of breeding at this time in R, niobe, R. verecundus, M. levipes, M. rubex, Pogonomys sylvestris, P. mollipilosus and probably Pogonomelomys sevia. Available evidence suggests that M. rubex varies in reproductive performance between years. Mean litter size is low in all species with mean live embryo counts from 3.09 in R. exulans to 1.09 in M. levipes and 0.75 in P. sevia. Pregnancy concurrent with lactation appears to be frequent in M. rufescens and perhaps P. sevia, and was noted on occasion in R, exulans, R, verecundus and M. levipes.